Blockage of arteries, such as the coronary arteries, can result in reduced blood flow to the downstream tissue, such as the heart muscle. In the case of the coronary arteries, such a blockage can lead to acute myocardial infarction or heart attack. Various treatments have been proposed to restore blood flow to the affected area, e.g., the ischemic myocardium. This process of restoring blood flow to the affected area is known as reperfusion.
Treatments that have been proposed to restore blood flow include thrombolytic therapy, percutaneous coronary intervention (PCI) and bypass surgery. Thrombolytic therapy involves the administration of therapeutic agents to open the blockage. Some thrombolytic agents that have been proposed or used include streptokinase, urokinase, and alteplase (recombinant tissue plasminogen activator, rtPA).
Percutaneous coronary intervention involves delivering a treatment device to the affected area of the blood vessel to open the blocked site. Commonly, an angioplasty procedure is performed in which a balloon catheter is tracked through the vasculature, and, once the balloon is at the constriction, the balloon is expanded to open the blockage. Often a stent is expanded and left at the site to help maintain the patency of the vessel.
Coronary artery bypass surgery involves a graft vessel being taken from the patient and implanted to bypass the area of blockage. Blood then is allowed to flow around the blockage through the bypass graft.
Reperfusion of blood flow to the ischemic tissue, while beneficial, can at times result in damage to the tissue. Because the affected tissue has been deprived of oxygen and nutrients, the restoration of blood flow can result in inflammation and oxidative damage. This is known as reperfusion injury.
Some techniques have been proposed to prevent and/or treat reperfusion injury. For example, glisodin has been proposed as a therapeutic treatment. However, there continues to be a need for improved techniques to prevent and/or treat reperfusion injury.
In addition to the foregoing, there is also a need for improved techniques for delivering therapeutic agent to a target location in a body. For example, there is a need for improved techniques for delivering therapeutic agent to prevent and/or treat reperfusion injury. As another example, there is a need for improved techniques for delivering therapeutic agent to tumors, e.g., for chemotherapy, particularly to hard to reach tumors. As another example, there is a need for improved techniques for delivering therapeutic agent for localized neuroprotection, such for delivering therapeutic agent to retinal ganglion cells for the prevention of glaucoma progression.